Study on Characteristics of Nozzle Jet Pump for Water Injection in Offshore Oilfield

Abstract

A single high-pressure water source by the throttling way to inject water into different pressure wells is often used in offshore water injection platform. It will cause huge energy consumption. Therefore, a new idea of using adjustable jet pump instead of pipeline valve was proposed. A water injection well in Bohai was regarded as the research object, and an adjustable jet pump was designed. The 3D model was established and the Realizable k-e turbulence model was used in Fluent to analyze how the nozzle-to-throat clearance and throat length affect the working performance of the jet pump. The reasonable structural parameters of nozzle-to-throat clearance and throat length were determined as 19.75 and 98 mm, respectively. To simulate the water injection process, the experiments of characteristic of the water injection pressure and flow rate when the nozzle opening varies as 50, 60, 70, 75, and 90% were carried out. Results show that when the water injection pressure ranges from 1.4 to 4.0 MPa, the water flow change from 605 to 273 m3/d with the 50% nozzle opening and the water flow changes from 803 to 657 m3/d with the 90% nozzle opening. By adjusting the nozzle opening, the adjustable jet pump can basically achieve the multiple combinations of injection pressure and flow. Compared with the existing water injection method, the new method can reduce energy consumption about 715 thousand kW-h per year.